﻿/*
* Copyright (c) 2010-2012 Tesla Engine Group
* 
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
* 
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* 
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/

using System;
using Tesla.Core;

namespace Tesla.Input {
    /// <summary>
    /// Keyboard static class that polls the current keyboard state. Usage is equivalent
    /// to directly using an IKeyboardWrapper.
    /// </summary>
    public static class Keyboard {
        private static IKeyboardWrapper _keyboardWrapper;

        static Keyboard() {
            Engine.Services.ServiceAdded += new EventHandler(ProviderChanged);
            Engine.Services.ServiceChanged += new EventHandler(ProviderChanged);
            Engine.Services.ServiceRemoved += new EventHandler(ProviderRemoved);
            CheckAndCreate();
        }

        /// <summary>
        /// Get the current state of the keyboard.
        /// </summary>
        /// <exception cref="Tesla.Core.TeslaException">Thrown if an IKeyboardProvider is not a registered service.</exception>
        /// <returns>Keyboardstate struct</returns>
        public static KeyboardState GetKeyboardState() {
            CheckAndCreate();
            return _keyboardWrapper.GetKeyboardState();
        }

        private static void ProviderChanged(Object service, EventArgs args) {
            if(service != null && service is IKeyboardProvider) {
                IKeyboardProvider provider = service as IKeyboardProvider;
                if(provider == null) {
                    throw new TeslaException("No keyboard input provider is set");
                }
                _keyboardWrapper = provider.KeyboardWrapper;
            }
        }

        private static void ProviderRemoved(Object service, EventArgs args) {
            if(service == null || service is IKeyboardProvider) {
                _keyboardWrapper = null;
            }
        }

        private static void CheckAndCreate() {
            if(_keyboardWrapper == null) {
                IKeyboardProvider provider = (IKeyboardProvider) Engine.Services.GetService(typeof(IKeyboardProvider));
                if(provider == null) {
                    throw new TeslaException("No input provider is set");
                }
                _keyboardWrapper = provider.KeyboardWrapper;
            }
        }
    }
}